Fluid simulation flows out of the shell
Some options. See which may apply to your situations.


I am not sure I agree with the -z setting for inflow as you currently wrote. 0 or +y seems more appropriate.  Fluid will flow with gravity.
Make your pipe thicker or surround the spout with an outflow.
If the fluid is only visible coming out of the pipe use a smaller pipe spout with more thickness.  One pipe for obstacle and no render. Another distinct pipe for render and not a fluid component.  This may preserve more resolution.
Make your pipe thicker while preserving internal wall.
See Fatten Shrink on the Blender Menus in edit mode.